The invention relates to an internal combustion engine control apparatus and control method, and more particularly to the control of the equivalent ratio when switching is done between stratified combustion and homogeneous combustion in an internal combustion engine capable of switching between these combustion modes in accordance with the driving condition.
In the Japanese laid-open patent application publication 10-331696, there is disclosure of the setting of the lower limit value of the equivalent ratio, in accordance with driving conditions, such as the engine speed, the load and the EGR ratio, immediately before switching from the stratified combustion to the homogeneous combustion.